Dying Alternator?
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CF Veteran
Joined: Jun 2011
Posts: 2,448
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From: Colorado
Year: 1992
Model: Cherokee
Engine: 4.0
Dying Alternator?
So I went out mudding today (pics will be posted later 
) and everything was fine until about later on my battery gauge was right next to the red area, at around 11v or so, it was noticeably low. I monitored it throughout the trail, and then shortly after that a humming type noise started back by my fuel tank. We all agreed that it sounds like a fuel pump acting up. When I was driving home, my check engine light came on, and then my RPM gauge wasn't moving. I ended up getting that working again, but pretty much drove home about an hour and a half off battery with the radio and stuff playing fine. I read that the alternators are good for about 200k miles, and I'm at 130k and put it through a lot, so I'm assuming it shortens the life.
Any ideas guys? Sorry if I left something out or described it wrong.
Thanks
) and everything was fine until about later on my battery gauge was right next to the red area, at around 11v or so, it was noticeably low. I monitored it throughout the trail, and then shortly after that a humming type noise started back by my fuel tank. We all agreed that it sounds like a fuel pump acting up. When I was driving home, my check engine light came on, and then my RPM gauge wasn't moving. I ended up getting that working again, but pretty much drove home about an hour and a half off battery with the radio and stuff playing fine. I read that the alternators are good for about 200k miles, and I'm at 130k and put it through a lot, so I'm assuming it shortens the life.Any ideas guys? Sorry if I left something out or described it wrong.
Thanks
Last edited by 92XJGuy; Aug 20, 2011 at 05:42 PM.
CF Veteran
Joined: Nov 2010
Posts: 5,841
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From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
Verify charging system either at a shop or with a meter. With a healthy charging system and battery, it should be in the 13.5 to 14.0 volt range.
Load test your battery. Load testing is the only accurate way of determining battery condition.
And be sure that all battery, alternator and ground connections are GOOD.
Load test your battery. Load testing is the only accurate way of determining battery condition.
And be sure that all battery, alternator and ground connections are GOOD.
CF Veteran
Joined: Oct 2009
Posts: 2,867
Likes: 16
From: Fauquier County, Virginia
Year: 1991
Model: Cherokee
Engine: I-6 4.0 HO
So I went out mudding today (pics will be posted later ) and everything was fine until about later on my battery gauge was right next to the red area, at around 11v or so, it was noticeably low. I monitored it throughout the trail, and then shortly after that a humming type noise started back by my fuel tank. We all agreed that it sounds like a fuel pump acting up. When I was driving home, my check engine light came on, and then my RPM gauge wasn't moving. I ended up getting that working again, but pretty much drove home about an hour and a half off battery with the radio and stuff playing fine. I read that the alternators are good for about 200k miles, and I'm at 130k and put it through a lot, so I'm assuming it shortens the life.
Any ideas guys? Sorry if I left something out or described it wrong.
Thanks
) and everything was fine until about later on my battery gauge was right next to the red area, at around 11v or so, it was noticeably low. I monitored it throughout the trail, and then shortly after that a humming type noise started back by my fuel tank. We all agreed that it sounds like a fuel pump acting up. When I was driving home, my check engine light came on, and then my RPM gauge wasn't moving. I ended up getting that working again, but pretty much drove home about an hour and a half off battery with the radio and stuff playing fine. I read that the alternators are good for about 200k miles, and I'm at 130k and put it through a lot, so I'm assuming it shortens the life.Any ideas guys? Sorry if I left something out or described it wrong.
Thanks
If you get a code 41 IIRC, then your alternator is dead. Replace it and be happy again. Mine did the same thing. Dropped to around 11-12v, CEL light gave me a 41 (or 42.. I honestly can't remember. It's the fault field circuit code).
Thread Starter
CF Veteran
Joined: Jun 2011
Posts: 2,448
Likes: 0
From: Colorado
Year: 1992
Model: Cherokee
Engine: 4.0
Verify charging system either at a shop or with a meter. With a healthy charging system and battery, it should be in the 13.5 to 14.0 volt range.
Load test your battery. Load testing is the only accurate way of determining battery condition.
And be sure that all battery, alternator and ground connections are GOOD.
Load test your battery. Load testing is the only accurate way of determining battery condition.
And be sure that all battery, alternator and ground connections are GOOD.
I'll try the key on/off thing to see if that helps narrow it down. And regarding the alternator, I'm not surprised. I was doing research because I was having a starting problem, thought it was my alternator, someone said it's fine until 200k, but that's not on a mudding Jeep. And for the record, a new starter fixed that issue.
Thanks guys
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